Depression erodes intimate relationships not just by making one person withdrawn, needy, or hostile, but also because it impairs a depressed person's ability to perceive the others' thoughts and feelings. It impairs what psychologists call "empathic accuracy" and that can exacerbate alienation, depression in a vicious cycle.

 A group of researchers set out to understand better these dynamics in relationships, particularly the role of gender.   The study in Psychological Science revealed what they call a surprising dynamic: "It's called the partner effect," said Reuma Gadassi, a psychology graduate student at the Hebrew University of Jerusalem. "Women's depression affects their own accuracy. But it also affected their partner's accuracy" - in both cases, negatively.

Fifty heterosexual couples, some married, some cohabiting, together an average of about five years, participated in the study. First, a questionnaire assessed their levels of depression. Then, their interpersonal perceptions were tested both in the lab and in daily life. 

In the lab, the couples were videotaped during a 12-minute conversation in which one sought help from the other. Halfway through, they switched roles: the help-requester became the helper. Afterwards, the individuals watched the tapes and wrote about their own thoughts and feelings and their partners'. The reports were assessed for similarities and differences between each person perceptions and the other's self-descriptions.

In the second portion, the participants made once-a-day diary entries for 21 days, rating a list of negative and positive moods and feelings about the relationship, both their own and their partner's, on a five-point scale. These entries were also assessed for "empathic accuracy."

From both tests, the researchers found that the more depressed the woman was, the less accurately she inferred her partner's feelings. In the daily-life portion, the specificity of depression's effect to negative (vs. positive) feelings was revealed. Men's own depression did not affect their empathic accuracy—though that is not to suggest that his blues would have no impact on the relationship, just "a different one," says Gadassi.

It was in the daily diaries that the most surprising finding emerged: When women were depressed and their sensitivities dulled, their partners also became less empathic. When women are depressed, the relationship suffers more. After all, mutual understanding is the bedrock of intimacy.

The study tells us, says Gadassi, "you can't understand depression without taking account of gender." The findings should inform treatment. "Bringing only the depressed woman into therapy is not enough," she says. "You really have to have both partners in the room."